One beautiful spring day several years ago, I traveled deep into the mountains of Chiapas with a group of conservationists to talk with local ranchers about cows—specifically, what they ate, and how. Around us the steep hillsides were nearly denuded. What grass remained was gray-brown. So many cattle trails crisscrossed the area that the hills looked as if they had been terraced by an ancient culture. It was among the most abused land Jeff and I had ever seen.

And yet in a small valley just below, some of the biggest cows we’d ever seen grazed on long, lush grasses. Suisse was the local term the ranchers used to describe them: well fed and healthy in all respects.

We had come to this impoverished state in southern Mexico to learn about a project that encourages farmers to use alternative grazing practices. This helps protect the land from the heavier, eroding rainfall the region is beginning to experience with climate change. It also enables the ranchers to raise healthier cows that produce richer milk, and more of it.

The previous evening our host for the gathering, a conservationist named Manuel had told Jeff and me about his efforts to convince ranchers to pasture their stock in fields of diverse native grasses, instead of the non-native grasses that had been used for generations but aren’t nearly as resilient. At first, Manuel said, the old school farmers wouldn’t listen. But he had persisted—quietly, I imagined, given his soft-spoken nature. He had spent long days with them, learning about their culture and their ways of farming and ranching, even meeting their families. One day a respected older rancher had agreed to plant some of his pasture in native grass, just to try Manuel’s methods. Others had followed suit.

The results had been every bit as impressive as Manuel had predicted.

Our group included two conservation biologists from Costa Rica, Muhammad and Claudia, who had experimented with similar grazing methods. They echoed Manuel’s thoughts: The most effective approach is to get to know local herdsmen, work alongside them as equals, and gently introduce new ideas.

There was one visitor who disagreed, a well-known scientist from Brazil. Short and square-bodied with a haughty expression, he’d published a book on grazing practices. During the three days we spent together, I came to call him El Experto.

The organizers of our tour hadn’t met El Experto before. They’d invited him based on his reputation. His work, they learned belatedly, had been mostly with large corporate-owned ranches that could afford to buy the costly equipment and fencing needed to move cows from pasture to pasture in an intensive program of grazing rotation. The ranchers in Chiapas employed a simple system of rotation that allowed grasses to recover sufficiently after grazing. But it was nothing like the maximum productivity model that El Experto had designed.

Problems surfaced in the first community we visited on the coast. Local cows had begun producing so much milk, thanks to their improved pasture, that a local cooperative had built a small cheese-making factory. Milk was heated on a burner, with propane generated from composted cow patties. The ranchers proudly showed us the in-ground composting tanks and the arrangement through which filtered propane was siphoned into a long metal pipe. This thin, fragile-looking pipe carried propane high over our heads and into the cheese-making facility. It was an ingenious arrangement, if dicey by U.S. safety standards. The liquid drawn from the composted manure was, the ranchers said, the best fertilizer in all the world. Inside the little factory, the metal vats and sinks for making cheese were sparkling clean.

I smiled at the president of the cooperative, who was leading the tour. “You must be very proud,” I said.

He smiled back.

El Experto didn’t share my enthusiasm. “Have you done a marketing study to see if you can sell this cheese?” he asked. “If not, you have wasted a great deal of time and effort. Also, you must use my record-keeping model if you want to get the most productivity from your work.”

Manuel, Claudia, and Muhammad looked on helplessly, shock on their faces.

Now we were meeting with nine other ranchers in a community high in the Sierra Madre de Chiapas. These men had stopped grazing cattle on the steep hillsides because of erosion and the great amount of effort it took the animals to climb up and down. Instead, they now pastured their animals on nutritious native grasses, cultivated in valley bottoms. They had also started harvesting some grass during the wet season and storing it in simple wooden silos. This millage was mixed with molasses for extra minerals. Local cows no longer went hungry in the dry season, and they were able to produce a reliable quantity of milk year-round—unusual in Chiapas.

We stood in a circle in the long grass, and one of the ranchers asked the visitors to briefly introduce ourselves. When it was El Experto’s turn, the lecture began. “You are wasting that land,” he said, pointing to the ugly gray-brown slopes above us. “With my method you could be grazing on them as well.”

Muhammad cut him off. “This is just to introduce yourself,” he said angrily.

“Let him speak,” one of the ranchers roared. “If he disagrees with what we’re doing, let him tell us why.”

El Experto continued for two minutes, using Spanish terms I didn’t recognize.

The ranchers’ discussion began with a brief description of their grazing methods and their commitment to using the best possible practices. Their polite tone was short-lived. A lanky man in a denim shirt turned to El Experto, whom he addressed with a sarcastic “Señor.”

“You work in a natural system that’s much wetter than ours,” he said. “We know our local conditions. You don’t.” Turning to us all, he said we shouldn’t come back into their valley unless we want to learn from them as well as teaching them.

A second rancher, more polite but clearly struggling to control his anger, talked for a few minutes about the specific needs of their livestock. No one from outside the region could know which practices would work best, he said.

As the group broke up, I walked back to the car next to Muhammad. He’d traveled widely and met with many ranching groups in Mexico and Central America. “Do you often get ranchers reacting so angrily?” I asked.

“Never,” he said. “I’ve never seen a group this antagonistic.”

It would be easy to dismiss El Experto as pompous and bullying, the kind of person we won’t often meet. I hated to think how he might have damaged the relationship between local ranchers and the conservation groups.

But here’s the truth: We all have strong ideas about how to help others. Too often we press them on people, rather than taking the time to learn if our ideas are appropriate for the need and circumstances. I’m certainly guilty of this, at least occasionally—and I should know better. I try to hold El Experto’s example in my mind as the ultimate cautionary tale. I don’t ever want to come close to being that pushy.

One last note: At the end of our tour, a number of grazing specialists were invited to a conference to give presentations on their work. They were each asked to speak no more than 25 minutes. El Experto spoke for 50 minutes and ignored all attempts to cut him off. His slides included pictures of himself with beautiful women hanging on him. He got plenty of laughs, and at the conclusion of the conference, a number of politicians and businessmen stood in line to purchase copies of his book.

The moral of this story: The most effective service work is often done by people on the ground, laboring quietly out of the limelight. It is to them that we owe the greatest thanks.